Explosive propellent powder



UNITED STATES PATENT OFFEQE.

FRANCIS I. no PORT, OF WILMINGTON, DELAWARE.

EXPLOSIVE PBOPELLENT POWDER.

No Drawing.

To all whom it may concern Be it known that I, FRANCIS I. DU Pox'r, a citizen of the United States, residing at Vilmington, county of Xew Castle, and State of Delaware, have invented a new and useful Improvement in Explosive Propellent Pow-.

der, of which the following is a full, clear, and exact description.

My invention comprises a smokeless propellent gun powder, which when used in a gun will materially reduce, almost to the point of elimination, the muzzle flash, which will. greatly lessen the erosion of the gun barrel, and which possesses a quality of safety against accidental ignition, not possessed by any propellent powder yet prod ced.

The reduction of the muzzle flash and the reduction of the erosive effect upon the gun are both produced by a reduction of the amount of carbon contained in the powder composition and by an increase of hydrogen, and the safety feature is due to a discovery which will be described farther on.

One pound of carbon, upon combining with oxvgen, produces approximately 14500 B. T. II, while one pound of hydrogen produces approximately 60000 B. T. U.

The temperature of dissociation of water (H O) into H +O is very much lower than that of CO into C-l-O or CO into C+O,. Therefore, although the number of T. U. per pound is much greater in the case of hydrogen burning to 11,0, nevertheless the actual temperature which the gases will reach in the act of combustion is less, the less the carbon and the more the hydrogen.

Nitrate of ammonia is an ideal substance for this purpose, but to make a propellent powder two thingsare required, namely:

1. Somesubstance which will help balance the .deficiency of combustible material; and

2. Something which will permit the formation of masses, or grains, as they are called, having definite thiclmess dependent upon the time of burning, length of the gun, etc. The first is a purely chemical requirement and the second purely mechanical. The substance which I have used for this purpose is nitrocellulose.

' lSIy new powder consists in nitrate of ammonia with just sufiicient colloided nitro cellulose to supply the requirements above mentioned.

4 In an application filed June 12, 1918,

Specification of Letters Patent.

Patented May 25, 1920.

Application filed April 28, 11919. Seriall'o. 293,099.

Serial No. 239.531, by Francis I. du Font and Ernest du Pont, some recognition of the advantages of nitrate of ammonia is recorded, but at that time, and until recently, the discovery which is the basis of this invention had notbeen made.

In the application j'ust referred to, 20%

nitrocellulose j is regarded as an absolute The reason for this was that it was known that nitrate of ammonia by itself is not inflammable, that when mixed with ignited by an ignition charge in a guncham; her. In other words, a certain amount of heat andpressure are required in order that the powder shall burn.

It has long been known that when nitrate of ammonia is mixed with (say) 10% of its weight of uncolloided nitrocellulose, mixtures are produced which, although they will not burn when a match is applied, will detonate when fired by a fulminate primer..

The discovery which is the subject of this invent on must not, however, be confused with these previously known qualities of detonating mixtures. The very fact that these are detonating mixtures would preclude even their trial as propllents in a gun.

In the manufacture of my propellent powder, I am careful to guard against those conditions which produce detonating mixtures. I do this by seeing-to it that the minute particles of nitrate of ammonia are embedded in a matrix of thoroughly colloided nitrocellulose. v

The preferred proportions are 92!; parts nitrate of ammonia to 7% parts of nit'ro cellulose.

The 7% parts of nitrocellulose are first thoroughly dissolved in a solvent, preferably amyl acetate. The proportion of amyl acetate may be varied somewhat, but I find that about 25 parts amyl acetate for the 11 parts nitrocellulose will work.

I prefer to use rather more amyl acetate than would be actually required for the mechanical operation of pressing the powder out into grains or pieces having the required web thickness. I prefer to do this even if, before the pressing operation, some of thesolvent is allowed to evaporate. In this way I insure that the'nitro'cellulose is thoroughly colloided and forms a matrix in which the nitrate of ammonia is embedded.

The proportions of nitrate of ammonia and nitrocellulose given above are not absolute, but may be varied within certain limits. The upper limit for the per cent. of nitrate of ammonia is that which will leave enough nitrocellulose to form a matrix. If this is exceeded, a powder would result the grains of which are too easily broken up. The lower limit would be that wherein the powder would possess no substantial advantage over known compositions.

The invention is not limited to the use of amyl acetate as a solvent, nor even to the use of nitrocellulose as the matrix material, but this is named as probablythe best of the comparatively few substances which are capable of forming a horn-like matrix after evaporation of the solvent.

The powder described above possesses certain well defined advantages over any so far produced. Besides being substantially .flashless and smokeless, it 1s less erosive to the guns. Accidental ignition in a magazine on board ship is far more unlikely than in the case of any known propellent explosive, and in the event of accidental fire, it would be possible, under conditions not too unfavorable, to put it out, whereas with all powders at present used the loss of the ship with all hands is the only possible result. The powder is very much cheaper than the present-day smokeless powders. One of the qualities of present-day smokeless powders that is most greatly feared is that they are all liable tothat kind of spontaneous decomposition which produces combustion. This is a quality of nitrocellulose which diminishes when it is mixed with substances which do not possess this quality. With this power, not only is the preponderance of nitrate of ammonia, which does not possess this quality, so great that the nitrocellulose is substantially deprived of the quality, but the danger is prevented by the fact that the powder cannot be ignited by such small amounts of heat as would be produced by slow decomposition of nitrocellulose.

Applicants invention does not depend primarily upon a particular combination of ingredients, but upon the physical condi.-

tion of the explosive. While compositions of a seemingly analogous character are known, they are known and used as high explosives and adapted for no .other use, largely because they are not sufliciently consolidated or compressed. Applicants invention involves the embedding of the main constituent of his explosive, in finely divided form, in a relatively small proportion of an ingredient adapted to fill the spaces between the particles and form a matrix which, when hardened, produces a hard and substantially non-porous mass, thereby producing not a high explosive, but a propel lent; that is, an explosive that willnot detonate, but will burn in the gun. I

It is, therefore, obvious that the mixture with ammonium nitrate of other ingredients for other purposes afford no disclosure of suggestion of applicants invention. For example, coating the particles of an ammonium nitrate explosive with a dry colloid for the purpose of rendering the ammonium nitrate non-hygroscopic, does not result in embedding the ammonium nitrate particles in a matrix, does not render the explosive substantially non-porous, and does give to the explosive the character of a propellent.

Indeed the addition to an ammonium nitrate powder of any substance that would merely cause the particles of ammonium nitrate to cake together, without consolida: tion, or elimination of the voids between particles, would merely impair 'or destroy the "alue of the powder as a'high explosive without imparting to the powder the quality of a propellent, and leave the high explosive quality of the ammonium nitrate unchanged.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. Apropellent explosive in solid form containing a greatly preponderating proportion of ammonium nitrate in admixture (with a relatively small proportion of an ingredient adapted to cause the particles to adhere and form a hard mass, the same being substantially smokeless, substantially flashless, and when not strongly confined substantially ignition-proof.

2. An explosive capable of use as a propellent in a gun, containing a greatly preponderatingproportion of ammonium nia relatively small proportion of an ingredient forming a matrix which when hardened produces a hard, substantially non-porous mass.

3. A propellent explosive "comprising a greatly preponderating proportion of ammonium nitrate in fine particles embedded in a matrix of material of horn-like hardness and having chemical qualities such that it will enter into the reaction of combustion.

11 trate in finely divided form, embedded in l cient proportion of colloided nitrocellulose to compensate for the deficiency of combustible material in the ammonium nitrate.

6. A propellent explosive containing more than eighty per cent. ammonium nitrate and a sufficient quantity of an ingredient adapted to compensate for the deficiency of combust-ible material .in the ammonium nitrate and forming a mixture in which the ammonium nitrate is embedded.

T. An explosive capable of use as a propellent in a gun containing as one ingredient a preponderating proportion of a material having :the quality, when used alone, of a high explosive, and containing as another ingredient nitrocellulose so combined with the first ingredient as to give the explosive the quality of a propellent, the nitrocellulose being in an amount less than will permit of spontaneous decomposition which produces fires.

. S. A propellent explosive composed of approximately 921,-% ammonium nitrate and 7:1 of colloided nitrocellulose.

In testimony of which invention, I have hereunto set my hand, at Philadelphia, Penna, on this Qlth day of April 1919.

- FRANCIS I. DU lONT. 

